Lubricating system for a gas turbine engine



Feb. 23, 1965 B. 'r. HOWES ETAL 3,170,292

LUBRICATING SYSTEM FOR A GAS TURBINE ENGINE Original Filed April 4. 1960 8 Sheets-Sheet 1 wvwwtow BENJAM/N HOWE 5 /l44/V M SWA TM A N Feb. 23, 1965 B 'r. HOWES ETAL 3,170,292

LUBRICATING SYSTEM FOR A GAS TURBINE ENGINE Original Filed April 4, 1960 8 Sheets-Sheet 3 Feb. 23, 1965 B. 'r. HOWES ETAL 3,170,292

LUBRICATING SYSTEM FOR A GAS TURBINE ENGINE Original Filed April 4. 1960 8 Sheets-Sheet 4 c i a W g Q E I iQ I w m BENJAMIN T HOWES ll AN M. SPMTMAN Feb. 23, 1965 a. T. HOWES ETAL 3,170,292

LU BRICATING SYSTEM FOR A GAS TURBINE ENGINE Original Filed April 4. 1960 8 Sheets-Sheet 5 O A O Q Q BEM/AM/N HOWES ll AN M SWAT/MAN Q 2 a WXW;

Feb. 23, 1965 B. r. HOWES ETAL 3,170,292

LUBRICATING SYSTEM FDR A GAS TURBINE ENGINE Original Filed April 4. 1960 8 Sheets-Sheet 6 BENJAMIN 7? H0 WES VAN M.SW47'MAN Feb. 23, 1965 B. T. HOWES ETAL LUBRICATING SYSTEM FOR A GAS TURBINE ENGINE Original Filed April 4. 1960 8 Sheets-Sheet 7 BENJAMIN T HOWES VAN M SWATMAN Feb. 23, 1965 B. T. HOWES ETAL LUBRICATING SYSTEM FOR A GAS TURBINE ENGINE Original Filed April 4, 1960 8 Sheets-Sheet 8 JUMP 7a2 237 m af j's 2 6 24 0/L I Q J P 000m;

lLT P 7 83 2/ 05 aoz 22 wuwwk u BENJAMIN .HOHES /V/4/V M. SWAT/MAN i 3gl7lk22- LUBRIQATING SYSTEM FOR A GAS Y TINE ENGINE, Y p Benjamin T. HowesandfIva'n 'M. Swatinan; Birmingham, lviichl, a'ssignors to'Ford Motor Company; Dearbem; 'Mieh.-, a corporation of Delaware U Original application Apr. 4, 1960;, Ser. No. 19,797." 'Divided and this application-Nov. 2.1, 196i); Ser,

No. 70,460 6 Ciaims: c1. cit-39:08)"

This invention relates to a gas-turbine engine 'and'more' particularlyfto a compact gas turbine engine s'uitable'for use inan'automotive vehicle. p

This. application'is aidi'vision of our copending application Serial'No. 19,797, entitled-Gas Turbine Engine,

filed April 4; 1960. y i

The'gas-tnrb'ineengine of the present invention includes a"low"pressure spo'olhaving a eompre ssor and a turbine, a high pressure spool having a compressor and a turbine, a'powerturb'ine, a primary burnenand a secondary or reheat burner. Additionally, it may include intercoolers connected 'between' the low pressure spoolcompressor and the high pressure spool ompresso1-, and recuperators" connected between the highpressure spool compressor and the primary burner;

The high pressure spool runs at a near constant speed? over most of the" load range'of the ehgine, from 70% of rated speedat' idle to 100%; of'ratedspeed at full power; The high'pre'ssure"spoolthus provides an excellent'power source'forthe accessories associated with the engine"ahdthe vehicle in WhlGlllhE engine is mounted; such as,en'gine oil pumps, power steering. pumps. and an electrical generator; The pumps and generator provide d canthi'ls be substantially smaller th'anthose employed 35 range of 70%l00%7 of the rated'speed of 'the high preswith conventional engines since they operate over a speed sure' spool; v I p The present invention'proyides' an interg rated lubricating systemfor the gas turbine engine ofthe present invention is provided for lubricating the bearings'supcatirlg' the various gear sets'employed- As previously mentioned, a plurality, of engine oil pumps are drivenby the highpressure spool at substantially a constant j45 of these pumps being 1 speed over a wide load range. It is prefer red to employ three pumps, with two connected to collection points. or sumps in the engine for deliverin'g oil to a common collection point or-sump which is connected to the third pump. The third pump delivers-oilunder pressure to the Various bearings and gear sets-that need lubrication, preferably through an oil filter and an oil cooler. An important feature ofthe lubrication system is the-provision of strategically-placed check valves which preventttie. oil in the system from draining into the various collection points orsumps when the engine is-at rest. Thus, all of the points of the en- FIG; 5 is a rear' eleyatioiial View; partially in section of the low pressure spool housing'jarid casing -with other portions 'ofthe engine being 'shown' in elevation;

FIG.I6"is a top plan'view of'theac'cssory gear box of of the'jpresentinvention; 1

FIG; 7 isa sectional'view taken along the. lines 7-'7 of FIG. 6;

FlG. 8' is a sectional View taken along the lines 8 -8 of FIG G; and

FIG. 9'is a diagrammaticillustration of the lubrication'systenifof the gas turbine engine of the presentinventiori.

Referring now to FIG. 1, air is taken into the gas turbine'en'gine of the present invention by means of arlow pressure compressor, preferablya centrifugal'compres sor' 11,'where it-is compressedp'rior todeli v ery to a pair:

of'twin scrolls 12and'13. The twin scrolls'divide the air" now fromth'e low pressure compressor for delivery to a pair of intercoolers, one of whichis shown'at; 14. These intercoolers are of the cross-flow air to air type; and are supplied cooling'air by a fanlo which delivers cooling air outwardly from the center; of the power plant'throu'gh the intercoole'r structure's. From the'intercoolers, the coled'air is recombined by means of a pair of ducts, oneof which is shown at 17, and is'then fed into the inlet chamber 21 of high pressure'spoolicompressor 22 whichis preferably of the centrifugal type. The high'pressure spool compressor further compresses the air and deliversit intoscroll 23;

The air from the:high:pressure sp ool compressor then dividedinto two flows paths by nieansof a pair of porting thevarious shaftsin theengi'ne and for lubri gine which need lubrication are adequately lubricated from the moment the engine is started.

An object 'ofthe present invention is the provision of an integrated lub'ri'catingsystem for a gas'turbine englhe'."

Other objectsand attendant advantages of the present invention will become more "readilyjappa'rent when the specification is considered in connection with theattached' drawings in which,

FIG; 1 is aperspectivefview'ofthei'gas'turbine engine of the'present invention with'portions cutaway;

FIGSL'Z and '3, when disposedin'side to side relationship, constitute a longitudinal sectional View ofthefgas turbine engine of the present invention;

FIG. 4'is a partial-longitudinal sectional view taken substantially normal to FIGS. 2 and 3;

iburner 31. J

The compressed air is then heated in the primary burner by the addition of fuel through the nozzle 34 (see FIG. 3) which' may be of the recirculating type.

The effluent from' the primary burner is then delivered toga highpr'essure turbine 35; which is preferably ofconduits; one of which is shoW'natZS, for delivery to a pair of recuperatorsjone of which is shown at 26. The heated air" from the recuperator's recombined in the primary burner '31 by means of conduits 32 and 33 which extend from the recuperators into either side of the the radiabinfi'ow' type; through a scroll-36 The high pressure turbine furnishes the power for driving the high pressure compressor andthese two devices together with the'shaft fo r supporting them is known as the high pressure spool. The gases from the high pressure. turbine are then delivered to a secondary orreheat burner 37' by means of a central conduit 38. The gases are then reheated toahi'gh temperature in the; reheat burner be-'., fore being fed to'a power turbine 41 through a scroll V assembly. 42 and. a nozzle assembly 43.

Fronrthe power turbine 41' the hot gases expand through a two-stage low pressure turbine, generally designated by the numeral '44, into. a diifuser 45. The ex haust gases are then split-and led into the recuperators,

one of which is shown at 26. As the exhaust gases flowthrough the recupefators heat; transfer takes place i between these exhaust gases, and the compressed air from the highpressure compressor 22 The cooled exhaust gases are then expelled to the atmosphere through exhaustfconduits one of which is shownat 46; The low pressure compressor '11; and the'low pressure turbine 44 toge'ther with'their interconnecting shaft form the low pressure spool.

Referringlnow'to FIGS 1; through 4, the low pressure spoolgthedow pressure spool housing and associated elements will be explained in greater detail; The low' pressure spool comprises the low pressure compressor 11, the two-stage low pressure turbine 44 and theiriterconnecting shaft which is designated by'the-numeral-Sl.

3 ,176,292? Patented Feb. 23,1965

The two-stage low pressure turbine 44 includes a first rotor 52 and a second rotor 53 with an interstage nozzle 54 interposed between them.

The low pressure spool is rotatably mounted in a low pressure spool housing 71 by means of sleeve bearings 72 and 73 and a double ball bearing 74. These bearings are suitably lubricated by means of a lubrication system which will be explained more in detail at a later point in the specification. Oil under pressure is supplied from this system to conduit 75 drilled in the low pressure spool housing 71. (See FIG. 4.) From this conduit the oil under pressure is supplied to the bearing 72, which is carried by bearing carrier 7 0, through conduit 76 drilled in the housing 71 and a pipe 77 which includes check valve 78. The sleeve bearing 73 is supported in a cylindrical sleeve 79 which is in turn supported by the low pressure spool housing. This sleeve has a longitudinal conduit 81 positioned therein which connects the sleeve bearing 73 to the oil under pressure in conduit 75 through conduit 82 drilled in the low pressure spool housing, transfer piece 83 and conduit 84 drilled in the sleeve.

Lubricating oil under pressure is also supplied to the double ball bearing 74 from the conduit 75 by means of conduits 86 and 87 in the low pressure spool housing 71, an annular passageway 88 in bearing carrier 89, passageway 91 in the bearing carrier and a transfer piece 92 connected to the passageway 91. The bearing carrier 89 is positioned within the low pressure spool. housing 71 and is affixed thereto, along with plate 63, by means of a plurality of bolts, one of which is shown at 90.

(See FIG. 2.) The transfer piece 92 directs oil upon the double ball bearing 74 and upon the mesh between bevel gear 93 affixed to the low pressure spool shaft 51 and the bevel gear 94 affixed to shaft 95, which interconnects the bevel gear 94 and the fan 16. The shaft 95 is formed from two pieces which are interconnected by a splined sleeve 96. Oil is also directed against the flange 61 of sleeve 60 via passageways 97 and 98 in the bearing carrier 89 to provide an anti-thrust bearing for the low pressure spool.

The gas turbine engine of this invention is provided with an oil sump 101 suitably afiixed to the bottom portion of the low pressure spool housing 71. Scavenge oil from the double ball bearing 74 falls downwardly through the cored portion of the housing 71 into this sump. Similarly, scavenge oil from the sleeve bearing 73 is directed into the sump 101 from chamber or auxiliary sump 102 and pipe 103 which connects the chamber 102 to an open space in the housing 71. A labyrinth seal is positioned adjacent the bearing 73 to prevent any oil from going down the shaft in the direction of the sleeve bearing 72. This labyrinth seal assures that the scavenge oil from the sleeve bearing 73 will find its way into the chamber 102. Scavenge oil from the sleeve bearing 72 falls into a chamber or auxiliary sump 104 positioned in the bearing carrier 70, and is then directed to a scavenge pump, which will be described at a later point in the specification, by means of pipes 105, 106 and a conduit 107, which is formed by drilling of the low pressure spool housing 71.

The high pressure spool housing 182 has aifixed thereto an accessory gear box housing, generally designated by the numeral 196. The accessory gear box is shown in FIGS. 6 and 7, and as shown in FIG. 7, has a plate 197 with a plurality of apertures 198 for receiving the bolts (not shown), to affix the accessory gear box housing to the high pressure spool housing. The accessory gear box also includes a bottom pan 200 afiixed to the housing 196 by a plurality of bolts 201 (FIG. 7).

As previously mentioned, the high pressure compressor 22 and the high pressure turbine 35 are combined in a back-to-back relationship, and are preferably one structural member. A shaft 205 extends from the compressor side of the combined compressor-turbine member, and issupported in the high pressure spool housing by means of a sleeve bearing, designated by the numeral 206. The shaft 205 is also supported in the accessory gear box housing by means of a double ball bearing 207. A gear 208 is affixed to the end of the shaft 205 by a nut 209, and this bevel gear meshes with another bevel gear 211 affixed to a shaft 212. A spur gear 213 affixed to the shaft 212 serves to drive a combined starter-generator for the engine, as well as a plurality of engine oil pumps which will be explained in detail at a later point in the specification.

Oil under pressure for lubricating the sleeve bearing 206 and the double ball bearing 207 is supplied from a conduit 216. From the conduit 216 oil flows into conduit 217 and to the sleeve bearing 206 through conduits 218 and 219. Oil for lubricating the bearing 207 flows into an annular channel 220, and a portion of this oil from the annular channel also flows through conduits 221 and 222 to lubricate the sleeve beaings 223 and 224 which support the shaft 212. Oil from the bearings 206, 207, 223 and 224 flows into the bottom of the accessory gear box housing and from there into the cored openings in the low pressure spool housing 71 by means of a conduit 225 which connects the accessory gear box housing with the low pressure spool housing. From the cored openings in the low pressure spool housing the oil then finds its way into the sump 101.

Referring now to FIGS. 6 through 8, there is shown the accessory gear box including the housing 196. As previously discussed, the accessory gear box housing supports a bevel gear 211 driven by the bevel gear 208 afiixed to the shaft 205 of the high pressure spool. The bevel gear 211 drives a spur gear 213 through the shaft 212. The spur gear 213 drives a combination starter-generator 231 through an idler gear 232 and a spur gear 233 affixed to a shaft 234 of the combination starter-generator. The spur gear 213 also drives three oil pumps, preferably of the Gerotor type, designated by the numerals 235, 236 and 237. The internal rotors of the Gerotor pumps are I mounted ,on a common shaft 238 having a spur gear 241 aflixed thereto. The spur gear 241 is driven by the spur gear 213 through an idler gear 242. The center section of the accessory gear box housing carries an oil filter 243,

which can, best be seen by reference to FIG. 2.

' FIG. 8 shows an enlarged view of the three Gerotor pumps 235, 236 and 237, and also discloses inlet conduits 244, 245 and 246 to these Gerotor pumps. Engine lubricating oil is received by the Gerotor pump 237 from the inlet 246 and is discharged to an outlet conduit 247. 'The connection of the outlet 247 to the remainder of the lubrieating system will be described at a later point in the specification. A pressure relief valve 248 is provided in the outlet conduit 247 to prevent unduly high pressures from being developed in the pump 237. Gerotor pump 236 receives oil from the inlet conduit 245 and the Gerotor pump 235 receives oil from the inlet conduit 244. Oil is discharged from these two pumps into chamber 251 in the accessory gear box housing (FIG. 7. The oil from the a chamber 251 then flows through an opening 252 into the bottom pan 200 of the accessory gear box housing where it is discharged into the cored opening in the low pressure spool housing 71 by means of the conduit 225, as was previously explained in connection with FIG. 2.

Referring specifically to FIG. 3, the power turbine 41 includes a shaft 416 which is rotatably supported in the reduction gear housing 301 by means of a pair of antifriction thrust bearings 417 and 418 and a sleeve bearing 433.

Lubricating oil is conveyed to the housing 301 from the lubrication system of the engine by way of a conduit 491 which is threaded into the housing at 492. From the conduit 491 lubricating oil is supplied to the bearing 433 via conduits 493, 494 and 495, oil transfer tube 496 and groove 497,. Lubricating oil is similarly supplied to the bearings 417 and 418 via conduits 493, 498, 501 and 502.

A planetary reduction gear train generally designated by the numeral "504 and shown in FIG. 3. is employed toreduce the speed. of the power turbine' shaft 416 so that usable speeds, to drive-a load, such as amotor vehicle, are

availableatthe'output shaft 412. This gearing is lubricated' with oil flowing through theconduits 493, 505 and 506., The lubricating oil usedinthe lubrication of the bearings 417, 418 and 433 and the gear train 504 falls to the bottom of the housing 301 and may be scavenged through the bore 507. i

. Referringnow to FIG. 9, there. is shown a diagrammatic 3' illustration ofthe lubrication system of the gasturbine engine of this invention. The lubrication system is provided with a main sump 101, which is shown in cross section in FIG. 2,.and-a pair of auxiliary sumps, one ofnected to-the bore or sump 507 by'means of a line 508- and the inlet conduit 244 shown inFIG. 8. The Gerotor pump-236k connected to the auxiliary sump 104, through the pipes 105, 106 and the bore 107 in the low pressure spool housing, shown in FIGS. 2 and 3, and by the inlet conduit 245. to the pump shown in FIG. 8. As previously pointed out in the discussion of FIGS. 7 and 8, the pumps 235 and 236 discharge into-chamber 251 located in the side. of accessorygear box housing 196. The chamber 251empties into thelower part of the accessory gear box housing: through the opening 252. The oil in the bottom of. the accessory gear box-housing 196 isthen returned to the main sump 101 'through the interconnecting conduit 225 which connects-the accessorygear box housing 1% with the low pressure spool'housing 71 and through the cored. openings in the low pressure spool housing. The sump 101-is connected to-the Gerotor pump 237 through a check-valve 771, shownin FIG. 2,'a pipe 772 secured to the low pressure'spool housing 71, and drilled conduits 773 and 774 in the low pressure spool housing.

Referringnow to FIG. 5, there is shown an external conduit 775 which is connected to the drilled conduit 774 in the low pressure spool housing at a point above the low pressuresp'ool andto the inlet conduit 246 for the Gerotor pump 237.

Lubricating oil from the .Gerotor pump 237is discharged into the opening-247 which is connected to filter 243 by means of .aline 781, shown in schematic form in FIG; 9. As the oil is filtered it is delivered toan oil cooler 782 which is connected to the output of the filter bymeans of a conduit783 which can be seen by referenceto FIG. 2. The oil cooler 782 may be positioned to receive cooling airfrom the intercooler fan 16.

The pressure relief valve 248, shown iii-FIG. 8, is connected with the discharge openingsfrom Gerotor pumps 235:and.236, and in case excessivepressures are built up in the pump. 237, this valve will open and discharge part of the output into the chamber 251 in theaccessory gear-box housing 196. A portionof the oil from the oil filter bypasses the oil cooler 782, and is directed onto thepoin-t where the bevel gears- 208 and'211 intermesh by means of conduit 784. The cooled-oil from the oil cooler is delivered into'a manifold791, as shown in- FIG. 5, from a conduit 792 which may be connected to the oil cooler by means of an oil line not shown. From the manifold 7191-, oil-is-delivered to lubricate the low.

reference to FIG. 4: From the conduit 75 oil is delivered under pressure to the bearings'72, .73' and 74 through the conduits previously described in connection with the description of FIGS. 2, 3 and'4.

, Oilunder pressure is also delivered'to the conduit 401,; as shown in. FIGS, by means of the conduit 793 and a,

conduit 794 which-is partially shown in FIG. 5. The

path of the oil from conduit 491 to the bearings and gears or. the power turbine. and the reduction gear train has been described previously in connection with FIG. 3.

Oil under. pressure.- is supplied to thehigh pressure spool beariugs206 and 207 through a conduit 801 (see FIG.- 5 )which is connected to the manifold 791 and is- I partially shown in FIG. 5. The conduit 801 is connected to supply oil under pressureto the opening 216, as shown in-FIG. 2, in the accessory gear box housing 196. The oil is then suppliedto bearings 206 and 207 as well as bearings 223 and 224 of the accessorygear box shaft 212 by-meansof the conduitsshown in FIG. '2 and previously described. Oil under pressure is also supplied to the sleeve bearings supporting the idler gears 2-32 and 242 ofthe accessory: gear box bymeans of a conduit 802 which conveys a portion of theoilflowing in conduit 801 to these bearings.

Check valves 78 and 771 are provided to prevent oil from-draining into the sump 104 and the sump 101; re-.

spectively, when the engine is shut down. The check valve 771 is an ordinary ball type check valve whichv permits oil to flow upwardly. through the conduit 774,

but will prevent oil from flowing in the reverse direction.

Thecheck valve 78, on the other hand, is a valve which requires a certain amount of pressure to open it, 'andwhen the engine is shut down the pressure of the oil in the lines above the check valve is'not suflicient to openit. These check valves insure adequate lubrication-forall pointsin the engine from the moment the engine is started.

It is apparent fromthe description of the lubricatingsystem for the gas turbine engine and from an inspectionofFIG. 9, that thepumps235 and 236 serve as scavenge pumps to pump. the. oil collected in auxiliary sumps 104- and 507 into the'main sump 101. The pump 237 then pumps" the oil from the main sump lubrication points. in the engine.

There is thus providedfor the gas turbine engine of this invention an integrated lubricating system for all of the bearings supporting all of the various shafts in the engine and-for the various gear sets employed. Additionally, there are-provided strategically placed check valves which prevent the oil in the system from draining into the various collection points when the engine isat rest.

It will be understood that the invention is not to be said bearings rotatably supporting said power turbineinsaid gasturbine engine-,said power turbinebeing adapted to power an external load, ahigh pressure spoolhousing, an accessory gearboxfhousing. afixed-to said high' pres- 'sure spool. housing, a high pressure spool,- a plurality of bearings rotatablysupportingsaid high pressure spool in said high pressure spool housing. and said accessory gear box housing, said accessory gear box housing having an opening-positioned therein communicating with the internal opening in said-low pressure spool housing, a main sump communicating with the opening in said low pressure spool housing, afirst auxiliary sump positioned to collect oil from the bearings supporting said powertur- 101 to the various bine, a second auxiliary sump positioned to collect oil from one of the bearings supporting said low pressure spool, the' oil from the remainder of the bearings supporting said low pressure spool being collected by said main sump, a first pump supported by said accessory gear box housing and having an inlet connected to said main sump and an outlet connected to supply all of said bearings with oil under pressure, a second pump supported by said accessory gear box housing and having an inlet connected to said first auxiliary sump, a third pump supported by said accessory gear box housing and having an inlet connected to said second auxiliary sump, said second and third pumps having outlets discharging into said accessory gear box whereby the oil discharged therefrom may flow through the opening therein, through the internal opening in said low pressure spool housing and into said main sump.

2. The gas turbine engine of claim 1 in which said first pump, said second pump and said third pump are driven by said high pressure spool.

3. A gas turbine engine comprising a low pressure spool housing having an internal opening positioned therein, a low pressure spool including a compressor, a turbine and an interconnecting shaft, said compressor being adapted to initially compress air taken into the gas turbine engine, a plurality of bearings rotatably supporting said low pressure spool within said low pressure spool housing, a power turbine, said power turbine being adapted to power an external load, a plurality of bearings, said bearings rotatably supporting said power turbine in said gas turbine engine, a high pressure spool housing, an accessory gear box housing afiixed to said high pressure spool housing, a high pressure spool, said high pressure spool housing, accessory gear box and high pressure spool being located vertically upwardly from said low pressure spool, a plurality of bearings rotatably supporting said high pressure spool in said high pressure spool housing and said accessory gear box housing, said accessory gear box housing having an opening positioned therein communicating with the internal opening in said low pressure spool housing, a main sump communicating with the opening in said low pressure spool housing, a first auxiliary sump positioned to collect oil from the bearings supporting said power turbine, a second auxiliary sump positioned to collect oil from one of the bearings supporting said low pressure spool, the oil from the remainder of the bearings supporting said low pressure spool being collected by saidmain sump, a first pump supported by said accessory gear box housing and having an inlet, a conduit connecting said main sump with said inlet, said first pump also having an outlet connected to supply all of said bearings with oil under pressure, a check valve positioned in said conduit adjacent said main sump permitting oil to flow from said main sump toward said first pump, but preventing flow from said first pump toward said main sump, a second pump supported by said accessory gear box housing and having an inlet connected to said first auxiliary sump, a third pump supported by said accessory gear box housing and having an inlet connected to said second auxiliary sump, said second and third pumps having outlets discharging into said accessory gear box whereby the oil discharged therefrom may flow through the opening therein, through the internal opening in said low pressure spool housing and into said main sump, and a gear set interconnecting said first, second and third pumps and said high pressure spool.

4. A gas turbine engine comprising a low pressure spool housing having an internal opening positioned therein, a low pressure spool including a compressor, a turbine and an interconnecting shaft, said compressor being adapted to initially compress air taken into the gas turbine engine, a plurality of bearings rotatably supporting said low pressure spool within said low pressure spool housing, a power turbine, said power turbine being adapted to power an external load, a plurality of bearings, said bear- 8 ings rotatably supporting said power turbine in said gas turbine engine, a high pressure spool housing, an accessory gear box housing atfixed to said high pressure spool housing, a high pressure spool, said high pressure spool housing, accessory gear box and high pressure spool being located vertically upwardly from said low pressure spool, a plurality of bearings rotatably supporting said high pressure spool in said high pressure spool housing and said accessory gear .box housing, said accessory gear box housing having an opening positioned therein communicating with the internal opening in said low pressure spool housing, a main sump communicating with the opening in said low pressure spool housing, a first auxiliary sump positioned to collect oil from the bearings supporting said power turbine, a second auxiliary sump positioned to collect oil from one of the bearings supporting'said low pressure spool, the oil from the re mainder of the bearings supporting said low pressure spool being collected by said main sump, a first pump supported by said accessory gear box housing and having an inlet, a conduit connecting said main sump with said inlet, a first check valve positioned in said conduit adjacent said main sump permitting oil to flow from said main sump toward said first pump but preventing flow in the reverse direction, said first pump also having an outlet, a plurality of conduits connected to said outlet to supply all of said bearings with oil under pressure including a conduit connected to supply oil to said one of said bearings supporting said low pressure spool, a second check valve positioned in said last mentioned conduit for permitting oil to flow from said first pump toward said one of said bearings but preventing flow of oil in the reverse direction, a second pump supported by said accessory gear box housing and having an'inlet connected to said first auxiliary sump, a third pump supported by said accessory gear box housing and having an inlet connected to said second auxiliary sump, said second and third pumps having outlets discharging into said accessory gear box whereby the oil discharged therefrom may flow through the opening therein, through the internal opening in said low pressure spool housing and into said main sump, and means interconnecting said first, second and third pumps and said'high pressure spool whereby said first, second and third pumps are driven by said high pressure spool.

5. In a gas turbine engine, a housing, a low pressure spool, .a plurality of bearings rotatably supporting said low pressure spool within said housing, a high pressure spool, said high pressure spool being located abovesaid low pressure spool in said engine, a bearing rotatably supporting said high pressure spool within said housing, an auxiliary sump positioned to receive lubricating oil from one of said bearings supporting said low pressure spool, a first pump and a second pump connected to a common shaft, a gear train interconnecting said common shaft and said high pressure spool, a housing enclosing said gear train and said first and said second pump, said first pump having an inlet connected to said auxiliary sump and an outlet connected to discharge lubricating oil into said last mentioned housing, said second pump having an inlet connected to said main sump and an outlet connected to deliver lubricating oil under pressure to the bearing of said low pressure spool and to the bearing of said high pressure spool, said housing enclosing said gear train and said pump being positioned above said main sump, and conduit means interconnecting said last mentioned housing with said main sump to permit lubricating oil to flow from said housing to said main sump under the force of gravity.

6. In a gas turbine engine, a housing, a low pressure spool, a plurality of bearings rotatably supporting said low pressure spool within said housing, a high pressure spool, a plurality of bearings rotatably supporting said high pressure spool within said housing, a power turbine, a plurality of bearings rotatably supporting said power turbine within said housing, said power turbine being adapted to power an external load, a first auxiliary sump positioned to receive lubricating oil from a plurality of bearings rotatably supporting said power turbine, a second auxiliary sump positioned to receive lubricating oil from one of the bearings supporting said low pressure spool, a main sump positioned to receive lubricating oil from the remainder of the bearings supporting said low pressure spool, a first pump, a'second pump and a third pump connected to a common shaft, a gear train interconnecting said common shaft and said high pressure spool, a housing enclosing said gear train' and said first pump, said second pump and said third pump, said first pump having an inlet connected to said first auxiliary sump and on outlet connected to discharge lubricating oil into said last mentioned housing, said second pump having an inlet connected to said second auxiliary sump and an outlet connected to discharge lubricating oil into said last mentioned housing, said third pump having an inlet connected to said main sump and an outlet connected to deliver lubricating oil under pressure to. the bearings of said low pressure spool, to the bearings of said high pressure spool and to the bearings of said power turbine, said housing enclosing said gear train and said pumps being positioned above said main sump,

. 1.0 i r r and conduit means interconnecting said housing with said main sump to permit lubricating oil to flow from said housing to said mainsump under the force of gravity.

References Cited in the file of this patent UNITED STATES lATENTS 2,402,467 Thompson June 18, 1946 2,672,278 Newcomb Mar. 16, 1954 2,693,248 Gaubatz Nov. 2, 1954 2,704,434 Schrnitt Mar. 22, 1955 2,749,087 Blackman et a1 June 5, 1956 2,751,749 Newcomb June 26, 1956 r 2,770,946 Savin Nov. 20, 1956 2,803,943 Rainbow Aug. 27, 1957 r 2,866,522 Morley et al. Dec. 30, 1958 2,913,069 Kubis Nov. 17, 1959 2,937,497 Clark May 24, 1960 2,951,337 Atkinson et a1 Sept. 6, 1960 2,988,884 Pouit June 20, 1961 FOREIGN PATENTS 690,120 Great Britain Apr. 15, 1953' 732,149 Germany Feb. 23, 1943 695,891 Great Britain Aug. '19, 1953 

1. A GAS TURBINE ENGINE COMPRISING A LOW PRESSURE SPOOL HOUSING HAVING AN INTERNAL OPENING POSITIONED THEREIN, A LOW PRESSURE SPOOL INCLUDING A COMPRESSOR, A TURBINE AND AN INTERCONNECTING SHAFT, SAID COMPRESSOR BEING ADAPTED TO INITIALLY COMPRESS AIR TAKEN INTO THE GAS TURBINE ENGINE, A PLURLITY OF BEARINGS ROTATABLY SUPPORTING SAID LOW PRESSURE SPOOL WITHIN SAID LOW PRESSURE SPOOL HOUSING, A POWER TURBINE, A PLURALITY OF BEARINGS, SAID BEARINGS ROTATABLY SUPPORTING SAID POWER TURBINE IN SAID GAS TURBINE ENGINE, SAID POWER TURBINE BEING ADAPTED TO POWER AN EXTERNAL LOAD, A HIGH PRESSURE SPOOL HOUSING, AN ACCESSORY GEAR BOX HOUSING AFFIXED TO SAID HIGH PRESSURE SPOOL HOUSING, A HIGH PRESSURE SPOOL, A PLURALITY OF BEARINGS ROTATABLY SUPPORTING SAID HIGH PRESSURE SPOOL IN SAID HIGH PRESSURE SPOOL HOUSING AND SAID ACCESSORY GEAR BOX HOUSING, SAID ACCESSORY GEAR BOX HOUSING HAVING AN OPENING POSITIONED THEREIN COMMUNICATING WITH THE INTERNAL OPENING IN SAID LOW PRESSURE SPOOL HOUSING, A MAIN SUMP COMMUNICATING WITH THE OPENING IN SAID LOW PRESSURE SPOOL HOUSING, A FIRST AUXILIARY SUMP POSITIONED TO COLLECT OIL FROM THE BEARINGS SUPPORTING SAID POWER TURBINE, A SECOND AUXILIARY SUMP POSITIONED TO COLLECT OIL FROM ONE OF THE BEARINGS SUPPORTING SAID LOW PRESSURE SPOOL, THE OIL FROM THE REMAINDER OF THE BEARINGS SUPPORTING SAID LOW PRESSURE SPOOL BEING COLLECTED BY SAID MAIN SUMP, A FIRST PUMP SUPPORTED BY SAID ACCESSORY GEAR BOX HOUSING AND HAVING AN INLET CONNECTED TO SAID MAIN SUMP AND AN OUTLET CONNECTED TO SUPPLY ALL OF SAID BEARINGS WITH OIL UNDER PRESSURE, A SECOND PUMP SUPPORTED BY SAID ACCESSORY GEAR BOX HOUSING AND HAVING AN INLET CONNECTED TO SAID FIRST AUXILIARY SUMP, A THIRD PUMP SUPPORTED BY SAID ACCESSORY GEAR BOX HOUSING AND HAVING AN INLET CONNECTED TO SAID SECOND AUXILIARY SUMP, SAID SECOND AND THIRD PUMPS HAVING OUTLETS DISCHARGING INTO SAID ACCESSORY GEAR BOX WHEREBY THE OIL DISCHARGE THEREFROM MAY FLOW THROUGH THE OPENING THEREIN, THROUGH THE INTERNAL OPENING IN SAID LOW PRESSURE SPOOL HOUSING AND INTO SAID MAIN SUMP. 